The Vector Development and Production Core occupies a pivotal role for this clinical gene therapy proposal. The challenges associated with production of adequate quantities of lentiviral vectors has been a major hurdle to their clinical application, even though the field has been aware for years that these vectors provide significant clinical advantages. Our Vector Core contributes two major elements to researchers wishing to use lentiviral vectors in the clinic: a state-of-the-art GMP production facility, fully staffed and actively producing lentiviral vectors, and a novel vector production system using stable cell lines developed in the Core and capable of producing over 100 liters of high titer >10^7 tu/ml), self-inactivating, clinical lentiviral vector supernatants in a single production run. We plan to produce at least three clinical batches of lentiviral vectors before 2011, with additional vectors being produced as they are developed and clinical testing becomes indicated. The first will be the CL20i4-EF1? -hYcOPT vector for the SCID-X1 clinical trial described in the project 3, Gene Therapy for X-Linked Severe Combined Immunodeficiency. Bioreactor production of this vector from a Master Cell Banked producer clone is already in progress, and a clinically certified product is expected to be ready for use by mid-2009. Other vectors expressing y-globin (described in project 1, Gene Therapy of Sickle Cell Disease through Enhancement of Fetal Hemoglobin) or WASp (described in project 2, Development of Gene Therapy for Wiskott-Aldrich Syndrome, are predicted to complete clinical production by the end of 2009 and 2010, respectively. In addition to the clinical vector production services, the Vector Core Laboratory will continue developing our stable producer cell system to facilitate the rapid and efficient derivation of cloned producer cell lines with newly designed vectors. Finally, as all three proposed research projects in this Program Project submission will involve clinical gene therapy with lentiviral vectors, the Vector Core will coordinate the critical analysis of patient samples for vector integration site distribution. We will first modify established PCR techniques currently in use in our research labs to facilitate sample analysis using the new massively parallel sequencing instrumentation available at St. Jude, and expand on our bioinformatic capability to manage the large data sets this technology generates Subsequently, the Vector Core will utilize our modified techniques to perform the FDA-recommended clonality assays on all treated patient tissue samples at regular intervals, and warehouse the integration site data sets to facilitate comparative analysis between different timepoints, patients, vectors, and clinical trials.